The 802.16m Amendment shall be developed in accordance with the P802.16 Project Authorization Request (PAR), as approved on 6 Dec. 2006, and with the Five Criteria Statement in IEEE 802.16-06/055r3. According to the PAR, the standard shall be developed as an amendment to IEEE Std. 802.16. This amendment provides continuing support for legacy WirelessMAN-OFDMA equipment.
In a conventional IEEE 802.16e system, a basic slot structure and a data region are defined as follows. A “slot” within an Orthogonal Frequency Division Multiple Access (OFDMA) physical layer (PHY) requires both time and sub-channel dimension for completeness and serves as the minimum possible data allocation unit. The definition of an OFDMA slot depends on the OFDMA symbol structure, which varies for UL (UpLink) and DL (DownLink), for FUSC (Full Usage of Sub-Channels) and PUSC (Partial Usage of Sub-Channels), and for the distributed sub-carrier permutations and the adjacent sub-carrier permutation (AMC).
For DL FUSC and DL optional FUSC using the distributed sub-carrier permutation, one slot is one sub-channel by one OFDMA symbol. For DL PUSC using the distributed sub-carrier permutation, one slot is one sub-channel by two OFDMA symbols. For UL PUSC using either of the distributed sub-carrier permutations and for DL TUSC1 (Tile Use of Sub-Channels 1) and TUSC2, one slot is one sub-channel by three OFDMA symbols. For the adjacent sub-carrier permutation (AMC), one slot is one sub-channel by two, three, or six OFDMA symbols.
In OFDMA, a data region is a two-dimensional allocation of a group of contiguous sub-channels, in a group of contiguous OFDMA symbols. At this time, logical sub-channels are allocated. Two-dimensional allocation may be visualized as a rectangle, such as is shown in FIG. 1.
In the related art, basic data allocation structures and/or pilot structures vary according to permutation rules such as PUSC, FUSC, AMC, etc. This is because permutation rules were separated in the time axis in the related art 16e system so that the structures were designed to be optimized according to each permutation rule. FIG. 2 shows an exemplary related art data allocation structure. Permutation rules are separated in the time axis in the related art method. However, if more than one permutation rules exist on the same time zone, one unified basic data allocation structure and pilot transmission structure are required.
When multiplexing 16e system and 16m system, it is desirable to design time-frequency granularity of a PRU of a 16m system so that the PRU of the 16m system is compatible with a 16e system. In addition, it is desirable to design multiplexing structures such that performance deterioration of each of the 16e system and the 16m system, which are multiplexed, be made as low as possible.
In addition, in an environment (in particular, in uplink) in which the 16e system and the 16m system are multiplexed and operated in a mixed mode in the same frame or the same sub-frame, available resource units or sub-channels need to be signaled to a mobile station (MS) of the 16m system. If a bitmap indicating available sub-channels among all sub-channels is signaled to the MS, the size of the bitmap is increased and thus signaling overhead is increased.